TREEISO  Tree Isomorphism
Given two undirected trees T1 and T2 with equal number of vertices N (1 ≤ N ≤ 100,000) numbered 1 to N, find out if they are isomorphic.
Two trees T1 and T2 are isomorphic if there is a bijection f between the vertex sets of T1 and T2 such that any two vertices u and v of T1 are adjacent in T1 if and only if f(u) and f(v) are adjacent in T2.
Input
The first line of input contains the number of test cases nTest (1<= nTest <= 400). Each test case contains:
 The first line contains the number of nodes N.
 Each of next N1 lines contain two integers A, B, denoting that there is an edge in T1 between nodes A and B (1 ≤ A, B ≤ N).
 Each of next N1 lines contain two integers A, B, denoting that there is an edge in T2 between nodes A and B (1 ≤ A, B ≤ N).
The sum of N over all test cases will not exceed 100,000.
Output
For each test case print YES if T1 and T2 are isomorphic and NO otherwise.
Example
Input: 2
4
4 2
4 1
2 3
4 2
2 3
4 1
5
3 4
3 2
3 5
3 1
3 4
4 2
2 5
2 1 Output: YES
NO
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acheron:
20101122 14:47:31
Are there other problems involving tree isomorphism ? 

Hy Trường Sơn:
20101111 15:40:58
Nice problem! 
Added by:  indy256 
Date:  20101110 
Time limit:  2s 
Source limit:  50000B 
Memory limit:  1536MB 
Cluster:  Cube (Intel G860) 
Languages:  All except: ASM64 